Sometimes you can use areas to find a theoretical probability.
Geometry A batter's strike zone depends on the height and stance of the batter. What is the geometric probability that a baseball thrown at random within the batter's strike zone, as shown in the figure below, will be a high-inside strike (one of the hardest pitches to hit)?
What are the favorable outcomes? All outcomes?
Favorable outcomes are points in the high-inside region. All outcomes are points in the strike zone.
For a baseball thrown at random in the batter's strike zone, the probability that it will be a high-inside strike is about 6.4%.